I wonder how many people are aware of NEC Section 404.2(C) that was implemented in the 2011 NEC. This provision requires that a grounded or neutral conductor be provided to any switch that controls lighting loads. The rational for this provision is that some electronic devices, such as motion sensors, require a stand-by current for operation. It is my opinion that this provision, as written, will cause more confusion than clarification. I have several reasons for this opinion.
• As far as I am aware, there are no electronic switching devices that can be used on a 3-way or 4-way switch.
• This provision, as written, will require that a grounded conductor be supplied to any switch location even if a sensor cannot be installed in that location, such as the case with 3-way and 4-way switches.
• In many instances, the power is brought to a 3-way switch, and the switch leg is run from the second 3-way switch to the light. In this instance, the grounded conductor is provided at both 3-way switches and possibly to one or more 4-way switches connected between the travelers. This would meet the requirement of 404-2(C), but there is still no way to install an electronic sensing device in any switch location, except the switch where power entered the switch box, and that is provided that a sensor for use in a 3-way switch location can be obtained. The other switches would have a grounded conductor, but no ungrounded conductor that can supply continuous power.
• In the event that power is supplied at the light fixture and a switch leg is run to one 3-way switch, it would now be necessary to use a three conductor cable between the light and one 3-way switch, and a four conductor cable between the two 3-way switches in order to supply a separate grounded conductor to the second switch. An electronic sensor can still not be used at either 3-way switch location.
• The National Electrical Code provides requirements for new installations. If a contractor knows that an electronic device is to be used at a particular location he would supply the proper power during the rough-in wiring.
• A major concern of the panel is that there have been instances where electronic sensors were installed in existing locations and the grounding conductor was used to complete the circuit back to ground. This is, of course, a very poor practice. However, this probably occurs in less than 0.1% of the switch locations through out the United States. Also, these electronic sensors require only milliamperes of current for operation. This new provision is like using a cannon to kill a fly.
I think 404-2(C) should be amended to require a grounded conductor at single-pole switch locations only, since these are the only locations where an electronic sensor can be use. I believe that this would make more sense than requiring a grounded conductor at all switch locations. However, I don’t think there is a way to do this before the 2014 code, so we are stuck with it.
I assume with this requirement a switch loop may no longer be used?
As far as I know, the only way a switch loop can be used is with 3 conductor cable to permit a neutral conductor to be present in the box.
I am again trying to get NEC 404.2(C) changed to something that makes a bit more sense. As you are probably